Aluminum-bronze alloy as raw materials for semi solid metal casting

ABSTRACT

An aluminum-bronze alloy as raw materials for Semi Solid Metal casting has a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, and P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities, further containing Si of 0.5 to 3 mass % as needed, and further containing one or more kinds of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass % as needed.

TECHNICAL FIELD

The present invention relates to an aluminum-bronze alloy as raw materials for Semi Solid Metal casting that can be used to produce an aluminum-bronze alloy cast having fine grains by Semi Solid Metal casting (semi-solid alloy casting) without agitating a molten metal.

Priority is claimed on Japanese Patent Application No. 2006-035004, filed Feb. 13, 2006, the content of which is incorporated herein by reference.

BACKGROUND ART

A Cu—Al copper alloy containing copper and aluminum as major components is known as an aluminum-bronze alloy. The aluminum-bronze alloy is a copper alloy with improved mechanical properties, corrosion resistance, wear resistance, fatigue resistance, and thermal resistance by adding Al of 10.5 mass % or less to Cu. It is generally known that this aluminum-bronze alloy is poor in casting property. However, since the aluminum-bronze alloy is excellent in mechanical properties, corrosion resistance, wear resistance, fatigue resistance, and thermal resistance, the aluminum-bronze alloy is used as a material of ship screws, screw shafts, pumps, chemical instruments, bearings, gears and the like.

It is generally known that the aluminum-bronze alloy is poor in casting property. The main reason results from a component composition thereof. Another reason for the low flowability of the molten metal is that dendritic a primary crystals are crystallized in the molten aluminum-bronze alloy. As a method of improving the deterioration in casting property due to the crystallization of the dendritic a primary crystals, a Semi Solid Metal casting method is known in which when a slurry-phase semi-solid aluminum-bronze alloy is produced by strongly agitating the molten aluminum-bronze alloy in a temperature range between the liquidus temperature and the solidus temperature and the semi-solid aluminum-bronze alloy is cast, dendrite generated in the solid-liquid mixture slurry is segmentalized by the agitation and the α primary crystal solid in the solid-liquid mixture slurry is formed in a sphere, thereby maintaining the flowability at a high solid phase ratio. Accordingly, it is possible to improve the casting property and to produce an aluminum-bronze alloy cast having a structure including fine grains and granular crystals (see Non-patent Document 1).

[Non-patent Document 1] “Fifth Revised Edition of Metal Manual,” edited by THE JAPAN INSTITUTE OF METALS, MARUZEN Co., Ltd. (published on Apr. 20, 1992), P1041 to P1042

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in executing the Semi Solid Metal casting method in which the molten metal is agitated, since it is necessary to perform the agitation under the control of a molten metal temperature, an apparatus needs to be increased in size. Accordingly, superfluous gas may be introduced into the molten metal under some conditions. The molten metal temperature needs to be lowered in consideration of wear damage. However, the generation of the dendrite structure cannot be completely suppressed even when the known aluminum-bronze alloy is agitated in a semi-solid state. Accordingly, the flowability of the molten metal is markedly deteriorated, thereby finally causing casting failure.

The invention is contrived in view of the above-mentioned problems. An object of the invention is to provide aluminum-bronze alloy as raw materials for Semi Solid Metal casting that can produce aluminum-bronze alloy cast having an excellent casting property and fine grains by the use of a Semi Solid Metal casting method without using a member for agitating the molten metal.

Means for Solving the Problems

Therefore, the inventors studied in order to enhance the flowability of the semi-solid aluminum-bronze alloy without using an agitating member for segmentalizing and granulating dendrite in a liquid phase and to produce an aluminum-bronze alloy cast having fine grains without casting failure even when the semi-solid aluminum-bronze alloy is cast at a low temperature. As a result, the following observations (A) to (D) were found out.

(A) A semi-solid aluminum-bronze alloy obtained by using aluminum-bronze alloy, which was obtained by adding Zr of 0.0005 to 0.04 mass % and P of 0.01 to 0.25 mass % to an aluminum-bronze alloy containing Al of 5 to 10 mass %, as a raw alloy, completely melting the aluminum-bronze alloy into a liquid phase, and cooling the molten aluminum-bronze alloy, and a semi-solid aluminum-bronze alloy obtained by re-melting the ingot and the like are both excellent in flowability. Accordingly, it was found that it is possible to produce an aluminum-bronze alloy cast having fine grains by casting the semi-solid aluminum-bronze alloy and that it is not necessary to perform an agitation process in a semi-solid alloy, unlike in the case of known examples.

(B) A semi-solid aluminum-bronze alloy obtained by using an aluminum-bronze alloy, which is obtained by adding Si of 0.5 to 3 mass % to the aluminum-bronze alloy according to (A) containing Zr of 0.0005 to 0.04 mass % and P of 0.01 to 0.25 mass %, as a raw alloy, completely melting the aluminum-bronze alloy into a liquid phase, and cooling the molten aluminum-bronze alloy, and a semi-solid aluminum-bronze alloy obtained by re-melting the ingot and the like are both excellent in flowability. Accordingly, it was found that it is possible to produce an aluminum-bronze alloy cast having fine grains by casting the semi-solid aluminum-bronze alloy and that it is not necessary to perform an agitation process in a semi-solid alloy unlike in the case of known examples.

(C) It was found that an aluminum-bronze alloy having a component composition further containing one or more of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass % in addition to the aluminum-bronze alloy according to (A) or (B) exhibits the same advantages.

(D) It was found that the reason for the excellent flowability in the semi-solid alloy state of the aluminum-bronze alloy according to (A), (B), or (C) is that fine and granular a primary crystals are generated instead of dendrite in the course of solidification.

The invention provides the following based on the above-mentioned study results:

(1) An aluminum-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass % and a balance of Cu and inevitable impurities.

(2) An aluminum-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Si of 0.5 to 3 mass %, and a balance of Cu and inevitable impurities.

(3) The component composition of the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to (1) or (2) may further contain one or more kinds of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass %.

ADVANTAGES OF THE INVENTION

When the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is melted to produce a semi-solid aluminum-bronze alloy in a solid-liquid mixture slurry and the semi-solid aluminum-bronze alloy is cast using a conventional method, a fine α primary phase is generated or an α solid phase coexists in the liquid phase of the semi-solid aluminum-bronze alloy. Accordingly, even when an agitating apparatus is not used, it is possible to cast the semi-solid aluminum-bronze alloy without damaging the flowability of the semi-solid aluminum-bronze alloy. In addition, it is an advantage that the crystal grains of the aluminum-bronze alloy cast obtained by casting the semi-solid aluminum-bronze alloy are further reduced in size, thereby further enhancing the mechanical strength.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the invention will be described in detail.

An aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention has a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities.

The aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention may have a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Si of 0.5 to 3 mass %, and a balance of Cu and inevitable impurities.

The aluminum-bronze alloy as raw materials for Semi. Solid Metal casting according to the invention may have a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Si of 0.5 to 3 mass %, and a balance of Cu and inevitable impurities and further containing one or more kinds of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass %.

An ingot of the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention, the component composition of which is adjusted, is produced and stored in advance, a semi-solid aluminum-bronze alloy is produced by re-melting a necessary amount of the aluminum-bronze alloy as raw materials, and a semi-solid aluminum-bronze alloy cast having fine grains can be manufactured by casting the semi-solid aluminum-bronze alloy.

The reasons for defining the component composition of the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention as described above will be described.

Al:

Al has a function of improving mechanical properties, corrosion resistance, wear resistance, fatigue resistance, and thermal resistance by means of the addition thereof to Cu, and a function of preventing the oxidation of Zr by means of its deoxidizing effect. When the content thereof is less than 5 mass %, it is not preferable because a sufficient effect cannot be obtained. On the other hand, when the content thereof is greater than 10 mass %, it is not preferable because the casting property is deteriorated and the obtained cast is hard and brittle, thus reducing the mechanical strength. Accordingly, the content of Al contained in the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 5 mass % to 10 mass %.

Zr:

With its coexistence with P, Zr has a function of promoting the generation of fine and granular α primary crystals in a semi-solid state, improving the flowability of the semi-solid aluminum-bronze alloy, and reducing the size of the crystal grains of the aluminum-bronze alloy cast. When the content thereof is less than 0.0005 mass %, it is not preferable because the reduction in size of the crystal grains is not sufficient. On the other hand, when the content is greater than 0.04 mass %, it is not preferable because the crystal grains of the cast increase in size. Accordingly, the content of Zr contained in the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 0.0005 mass % to 0.04 mass %.

P:

With the coexistence of Zr, P has a function of promoting the generation of fine and granular a primary crystals in a semi-solid state, improving the flowability of the semi-solid aluminum-bronze alloy, and reducing the size of the crystal grains of the aluminum-bronze alloy cast. When the content thereof is less than 0.01 mass %, it is not preferable because the reduction in size of the crystal grains is not sufficient. On the other hand, when the content is greater than 0.25 mass %, it is not preferable because intermetallic compounds with a low melting point are generated, making it brittle. Accordingly, the content of P contained in the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 0.01 mass % to 0.25 mass %.

Si:

Si has a function of further improving the flowability of the semi-solid aluminum-bronze alloy, lowering the melting point, and enhancing corrosion resistance, strength, and machinability and thus is added as needed. When the content thereof is less than 0.5 mass %, it is not preferable because a desired effect cannot be obtained. On the other hand, when the content is greater than 3 mass %, it is not preferable because the flowability of the cast decreases and is brittle. Accordingly, the content of Si contained in the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 0.5 mass % to 3 mass %.

Other Components:

The aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention may further contain one or more kinds of Pb, Bi, Se, and Te as needed. When the components are contained in the aluminum-bronze alloy, it is preferable that the content of Pb be in the range of 0.005 mass % to 0.45 mass %, the content of Bi be in the range of 0.005 mass % to 0.45 mass %, the content of Se be in the range of 0.03 mass % to 0.45 mass %, and the content of Te be in the range of 0.01 mass % to 0.45 mass %.

By making the aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to the invention have the above-mentioned component composition, when the aluminum-bronze alloy as raw materials for Semi Solid Metal casting is melted to produce a semi-solid aluminum-bronze alloy in a solid-liquid mixture slurry and the semi-solid aluminum-bronze alloy is cast using a conventional method, a fine and granular a primary phase is generated or an α solid phase coexists in the liquid phase of the semi-solid aluminum-bronze alloy. Accordingly, even when an agitating apparatus is not used, it is possible to cast the semi-solid aluminum-bronze alloy without damaging the flowability of the semi-solid aluminum-bronze alloy. In addition, it is an advantage that the crystal grains of the aluminum-bronze alloy cast obtained by casting the semi-solid aluminum-bronze alloy are further reduced in size, thereby further enhancing the mechanical strength.

EMBODIMENTS Embodiment 1

By preparing conventional cathode copper as a raw material, feeding the cathode copper into an electrical furnace, melting the cathode copper in an atmosphere of Ar gas, adding Al and P thereto when the temperature of the molten copper is 1200° C., adding Si, Pb, Bi, Se, Te, and the like thereto as needed, and finally adding Zr thereto, a molten aluminum-bronze alloy was produced. By casting the molten aluminum-bronze alloy, ingots of aluminum-bronze alloys as raw materials for Semi Solid Metal casting (hereinafter, referred to as aluminum-bronze alloys as raw materials according to examples of the invention) according to Examples 1 to 45 of the invention and aluminum-bronze alloys as raw materials for Semi Solid Metal casting (hereinafter, referred to as aluminum-bronze alloys as raw materials according to comparative examples) according to Comparative Examples 1 to 6, which have the component compositions shown in Tables 1 to 4, were produced.

By melting an aluminum-bronze alloy, which contains Al of 9 mass % and a balance of Cu and inevitable impurities and is available on the market, in an atmosphere of Ar gas, a molten aluminum-bronze alloy of a temperature of 1200° C. was produced. By casting the molten aluminum-bronze alloy, an ingot of a conventional aluminum-bronze alloy as raw materials for Semi Solid Metal casting (hereinafter, referred to as a conventional aluminum-bronze alloy as raw materials) having the component composition shown in Table 4 was produced.

By cutting out parts of the ingots of the aluminum-bronze alloys as raw materials according to Examples 1 to 45 of the invention, the aluminum-bronze alloys as raw materials according to Comparative Examples 1 to 6, and the conventional aluminum-bronze alloy as raw materials and heating the cut-out ingots at a predetermined temperature between the solidus temperature and the liquidus temperature to re-melt the ingots, semi-solid aluminum-bronze alloys were produced. Quenched samples were produced by rapidly quenching the semi-solid aluminum-bronze alloys. By observing the structures of the quenched samples with an optical microscope, the shapes of the α solid phase coexisting with the liquid phase in the semi-solid aluminum-bronze alloy were estimated and the average grain sizes thereof were measured. The results are shown in Tables 1 to 4.

The average grain sizes of the α solid phase were measured by etching the cutting surfaces of the quenched samples with nitric acid and then observing the cutting surfaces with an optical microscope.

TABLE 1 α solid phase in quenched sample Aluminum-bronze Average alloy as raw Component composition (mass %) grain size materials Al Zr P Si Pb Bi Se Te Cu shape (μm) Examples 1 5 0.0008 0.08 — — — — — balance granular 200 of the 2 6 0.0015 0.01 — — — — — balance granular 200 Present 3 7 0.006 0.07 — — — — — balance granular 60 Invention 4 8 0.0094 0.05 — — — — — balance granular 40 5 9 0.015 0.09 — — — — — balance granular 60 6 10 0.018 0.11 — — — — — balance granular 120 7 8 0.0008 0.11 0.5 — — — — balance granular 100 8 9 0.0015 0.16 1 — — — — balance granular 90 9 7 0.006 0.13 3 — — — — balance granular 80 10 5 0.0008 0.08 — 0.43 — — — balance granular 200 11 8 0.0015 0.01 — 0.35 — — — balance granular 150 12 10 0.006 0.07 — 0.23 — — — balance granular 100 13 7 0.018 0.11 — 0.01 0.12 — — balance granular 40 14 6 0.028 0.13 — — 0.43 — — balance granular 100 15 7 0.039 0.19 — — 0.35 — — balance granular 150

TABLE 2 α solid phase in quenched sample Aluminum-bronze Average alloy as raw Component composition (mass %) grain size materials Al Zr P Si Pb Bi Se Te Cu shape (μm) Examples 16 9 0.003 0.21 — — 0.23 — — balance granular 120 of the 17 8 0.0015 0.16 — — 0.01 0.05 — balance granular 100 Present 18 10 0.006 0.13 — — 0.005 0.06 0.01 balance granular 120 Invention 19 5 0.0008 0.08 — — — 0.11 — balance granular 200 20 8 0.0015 0.01 — 0.1 — 0.06 — balance granular 200 21 10 0.006 0.07 — — — 0.21 — balance granular 150 22 7 0.018 0.11 — — — 0.35 — balance granular 40 23 6 0.028 0.13 — 0.005 0.005 0.03 0.01 balance granular 100 24 7 0.039 0.19 — — 0.005 — 0.11 balance granular 150 25 9 0.003 0.21 — 0.005 — — 0.05 balance granular 120 26 8 0.0015 0.16 — — — — 0.45 balance granular 100 27 10 0.006 0.13 — — — — 0.35 balance granular 150 28 5 0.0008 0.08 3 0.43 — — — balance granular 100 29 8 0.0015 0.01 1 0.35 — — — balance granular 200 30 10 0.006 0.07 0.5 0.23 — — — balance granular 150

TABLE 3 α solid phase in quenched sample Aluminum-bronze Average alloy as raw Component composition (mass %) grain size materials Al Zr P Si Pb Bi Se Te Cu shape (μm) Examples 31 7 0.018 0.11 3 0.01 — — 0.01 balance granular 35 of the 32 6 0.028 0.13 5 — 0.43 — — balance granular 45 Present 33 7 0.039 0.19 2 — 0.35 — — balance granular 150 Invention 34 9 0.003 0.21 3 — 0.23 — — balance granular 100 35 8 0.0015 0.16 2 — 0.01 — — balance granular 100 36 10 0.006 0.13 3 — 0.005 — — balance granular 150 37 5 0.0008 0.08 2 — — 0.11 — balance granular 150 38 8 0.0015 0.01 3 0.009 0.005 0.06 — balance granular 200 39 10 0.006 0.07 4 — — 0.21 — balance granular 150 40 7 0.018 0.11 3 — — 0.35 — balance granular 35 41 6 0.028 0.13 5 0.005 0.005 0.03 0.01 balance granular 45 42 7 0.039 0.19 2 — — — 0.11 balance granular 120 43 9 0.003 0.21 3 0.005 — 0.03 0.05 balance granular 100 44 8 0.0015 0.16 2 — — — 0.45 balance granular 100 45 10 0.006 0.13 3 — — — 0.35 balance granular 150

TABLE 4 α solid phase in quenched sample Aluminum-bronze Average alloy as raw Component composition (mass %) grain size materials Al Zr P Si Pb Bi Se Te Cu shape (μm) Comparative 1  4* 0.015 0.05 — — — — — balance granular 400 Examples 2 11* 0.015 0.05 — — — — — balance dendrite-phase — 3 7 0.0003* 0.05 — — — — — balance dendrite-phase — 4 7 0.042* 0.04 — — — — — balance granular 400 5 7 0.009 0.008* — — — — — balance dendrite-phase — 6 7 0.005 0.26* — — — — — balance dendrite-phase — Conventional 9 — — — — — — — balance dendrite-phase — Example *Mark represents a value departing from the invention

It is estimated from the results shown in Tables 1 to 4 that the fine granular α solid phase coexists with the liquid phase in the semi-solid state of the aluminum-bronze alloys as raw materials according to Examples 1 to 45 of the invention, since the α solid phases of the quenched samples were all fined granular. On the other hand, it is estimated that dendrite was generated in the semi-solid state of the conventional aluminum-bronze alloy as raw materials, since the α solid phase of the quenched sample was all in a dendrite phase.

Accordingly, it can be seen that the semi-solid aluminum-bronze alloys produced from the aluminum-bronze alloys as raw materials according to Examples 1 to 45 of the invention were better in terms of fluidity than the semi-solid aluminum-bronze alloy produced from the conventional aluminum-bronze alloy as raw materials and that a fine granular α solid phase was generated in the liquid phase of the semi-solid aluminum-bronze alloy obtained by melting the aluminum-bronze alloys as raw materials according to Examples 1 to 45 of the invention, thereby obtaining a cast having fine grains even when the semi-solid aluminum-bronze alloy was cast without agitation. It can be also seen that the aluminum-bronze alloys as raw materials according to Comparative Examples 1 to 6 containing Al, Zr, and P that depart from the condition of the invention (the range of component composition of the invention) were not preferable since dendrite was generated, a reduction in size of the crystal grains was insufficient in the semi-solid state thereof, or the alloys were brittle.

Embodiment 2

By cutting out parts of the ingots of the aluminum-bronze alloys as raw materials according to Examples 1 to 45 of the invention, produced in Embodiment 1, the aluminum-bronze alloys as raw materials according to Comparative Examples 1 to 6, and the conventional aluminum-bronze alloy as raw materials and completely melting the cut-out ingots, molten aluminum-bronze alloys in a liquid phase were produced. Semi-solid aluminum-bronze alloys maintained at a predetermined temperature between the solidus temperature and the liquidus temperature were produced by cooling the molten aluminum-bronze alloy thereafter. Quenched samples were produced by rapidly quenching the semi-solid aluminum-bronze alloys. By observing the structures of the quenched samples with an optical microscope, the shapes of the α solid crystals generated in semi-solid aluminum-bronze alloys were estimated and the average grain sizes thereof were measured. The results were the same as in Embodiment 1.

While exemplary embodiments of the invention have been described, the invention is not limited to the embodiments. The elements of the embodiments may be added, omitted, replaced, or modified without departing from the gist of the invention. The invention is not limited to the above description, but is defined only by the appended claims.

INDUSTRIAL APPLICABILITY

According to the aluminum-bronze alloy as raw materials for Semi Solid Metal casting of the invention, it is possible to produce an aluminum-bronze alloy cast having fine grains without casting failure occurring even when the semi-solid aluminum-bronze alloy is cast at a low temperature, by improving the flowability of the semi-solid aluminum-bronze alloy without using a molten metal agitating instrument. 

1. An aluminum-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities.
 2. An aluminum-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Al of 5 to 10 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Si of 0.5 to 3 mass %, and a balance of Cu and inevitable impurities.
 3. An aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to claim 1, wherein the component composition further contains one or more kinds of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass %.
 4. The aluminum-bronze alloy as raw materials for Semi Solid Metal casting according to claim 2, wherein the component composition further contains one or more kinds of Pb of 0.005 to 0.45 mass %, Bi of 0.005 to 0.45 mass %, Se of 0.03 to 0.45 mass %, and Te of 0.01 to 0.45 mass %. 